In a nutshell, the "trick" is to place all the files from a
particular linux distribution into a single directory and then
chroot into that directory to
develop/test/debug your program. This approach will work provided
that:

The kernel version of the "main" or "primary" distribution that you
are running is (at least somewhat) compatible with the "secondary"
or chroot'ed distributions, and

Your application is primarily user-space (ie. no kernel modules)
and does not depend intimately on any particular kernel features
(ie. /proc behavior).

Given those assumptions, the following outline is one way to setup
the multiple secondary Linux distributions that will be used for
development, testing, or other purposes:

First, create or locate an unused partition on one of your hard
drives that is large enough (usually 2--4Gb is sufficient) to do a
basic install of one of the secondary Linux distributions.

Install the secondary distro into this partition but do not add it
to your boot configuration. Note that this install need only
include the packages that your target application (or tests)
require. For instance, you may be able to ignore applications such
as the X server or other space-hogs.

Reboot your primary Linux distribution and mount the partition
containing the freshly-installed "secondary" distro. Copy
(preferably using tar -cp or some other
method that preserves permissions) all the files from the secondary
distro to a location such as /opt/distros/DISTRO_NAME.

Repeat steps 2--3 for any additional distributions that you wish to
install. The result should be a directory structure resembling:

It is important to use a 2.4-series or newer Linux kernel in the
"primary" Linux distribution in order to take advantage of the
multiple mount points feature that the 2.4-series permits. For many
tasks, the /proc and /tmp filesystems will have to be remounted in the
secondary distribution using:

to obtain a shell with one of the secondary distros. Note
that the xhost command is only necessary
if you intend to use X-windows applications.

Finally, create a user (if necessary) within the chroot-ed shell and develop, build, and/or test
your application within this "separate" Linux distribution! Not
that you may also have to specify your DISPLAY environment variable if you'd like to use X
applications.

Done! You now have a shell that is, for all practical purposes,
running within the secondary Linux distribution of your choice.